The impact of heat treatment on E. coli cell physiology in rich and minimal media considering oxidative secondary stress.

Aims: This study investigates the cell physiology of thermally injured bacterial cells, with a specific focus on oxidative stress and the repair mechanisms associated with oxidative secondary stress.

Methods And Results: We explored the effect of heat treatment on the activity of two protective enzymes, levels of intracellular reactive oxygen species, and redox potential. The findings reveal that enzyme activity slightly increased after heat treatment, gradually returning to baseline levels during subculture.

Evaluation of distinct modes of oxidative secondary injury generated in heat-treated cells of Escherichia coli with solid/liquid and complex/semi-synthetic media sets.

Aims: To characterize and evaluate oxidative secondary injury generated in heat-treated Escherichia coli cells during recovery cultivation either on agar or in a broth of a semi-synthetic enriched M9 (EM9) medium and a complex Luria broth (LB) medium with different types of antioxidants.

Methods And Results: E. coli cells grown in the EM9 and LB broth were heated at 50°C in a buffer (pH 7.

Detection Time Distribution of Microcolonies Formed by Individual Heat-Injured Cells of Escherichia coli.

The microcolony formation at 30℃ on an enriched minimal salts agar plates by individual Escherichia coli cells heated at 50℃ was monitored with a time-lapse shadow image analysis system, MicroBio μ3D AutoScanner. While the time course of microcolony count detected every half an hour for the unheated cells seemingly demonstrated a normal distribution, that for the heated cell population demonstrated totally the growth delay probably resulting from cell injury and also interestingly distributed in its rather deformed pattern with a tailing. Those patterns of the cumulative counts of appearing microcolonies during the post-heating cultivation period were expressed in three different mathematical models.